Space Weathercamera set for launch in 2000

Space weather camera set for launch in 2000

Scientists will start the millennium with a new IMAGE
of the magnetosphere

Feb. 16, 1999:
A unique camera that will take some of the first pictures
of Earth's invisible magnetic shield is being prepared for flight
on Feb. 15, 2000. The mission, called IMAGE, will explore a region
of space where the aurora is energized.

"It's exciting to be in a position where you know you're
going to stumble onto things you didn't suspect were there,"
said Dr. Dennis Gallagher at NASA's Marshall Space Flight Center.

Right: An artist's concept of the Imager for
Magnetopause-to-Aurora Global Exploration (IMAGE) satellite.

That's because in the 41 years that scientists have been studying
the magnetosphere - the immense cloud of ionized gas formed by
Earth's magnetic field - scientists have never gotten a picture
of it. Somewhat like being in a massive fog, they have taken
countless measurements throughout the magnetosphere, and taken
pictures of its effects on the upper atmosphere. But the overall
shape of the magnetosphere can only be inferred from those data.

The view from afar

One of the first images of the
geocorona was taken in 1972 by astronaut John Young while on
the Moon. The Apollo 16 mission carried a U.S. Navy ultraviolet
camera that observed the stars and also produced this striking
photo (far left) of hydrogen in the plasmasphere around the Earth.
It was colorized (left) to show brightness variations.

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Computer simulations depict how
IMAGE will reveal the magnetosphere in (left to right) light
emitted by neutral atoms, radio echoes, extreme ultraviolet,
and far ultraviolet.

Stepping back for a better view

Gallagher is a co-investigator for the Imager for Magnetopause-to-Aurora
Global Exploration (IMAGE) satellite scheduled for launch from
Vandenberg Air Force Base, Calif., on Feb. 15, 2000. IMAGE will
be the first satellite that will let scientists step back and
take pictures of the magnetosphere as it changes shape.

The Earth's magnetic field acts as a buffer between the terrestrial
environment and the solar wind. The two best known effects of
the magnetosphere are the aurora borealis and the Van Allen radiation
belts.

The aurora is caused by electrons and ions zinging back and
forth along the magnetic field lines and reversing course when
they hit a "mirror" point. When energized by a solar
storm, these particles can punch through the mirror points and
hit the outer atmosphere, causing the aurora's enchanting glow.
The Van Allen belts, named for discoverer James Van Allen, can
disrupt the electronics of satellites.

Left: IMAGE
will be placed in an orbit that loops high above the Northern
Hemisphere to provide wide views of the aurora borealis and the
inner magnetosphere. The elliptical orbit will precess during
the 2-year mission.

These solar-terrestrial effects can also disrupt communications,
cause massive power outages, and even corrode long-distance pipelines.
As a result, the magnetosphere has been studied closely since
Van Allen's discovery in 1958. Knowing the shape of the magnetosphere
and how it changes in response to the solar wind will help scientists
in predicting what the effects will be here on Earth. IMAGE's
objectives are:

Identify the dominant mechanisms for injecting plasma into
the magnetosphere on substorm and magnetic storm time scales,

Determine the directly driven response of the magnetosphere
to solar wind changes, and,

Discover how and where magnetospheric plasmas are energized,
transported, and subsequently lost during substorms and magnetic
storms.

To do that, IMAGE
will be launched into an orbit that loops from a low point of
1,000 km (600 mi) to a high point of almost 45,000 km (almost
27,000 mi). From that vantage point, IMAGE's instruments will
look back and be able to see the inner structure of the magnetosphere,
including the magnetopause, the boundary where the magnetosphere
meets interplanetary space.

Right: A cutaway diagram of the magnetosphere illustrates
how IMAGE will observe the magnetosphere.

Assembling an IMAGE

Among the instruments will be the Wideband Imaging Camera
(WIC) provided by NASA/Marshall. Science and engineering teams
at NASA/Marshall recently completed testing and calibrating the
WIC and sent it to the University of California at Berkeley which
integrated it into the full collection of far-ultraviolet cameras.

That assembly now is at Southwest Research Institute in San
Antonio, Texas, for integration onto the instrument deck plate
and more testing. Finally, the assembly will be sent to Lockheed
Martin in Sunnyvale, Calif., for final assembly of the spacecraft,
and then to Vandenberg Air Force Base, Calif., for launch.

"The WIC is an unusual instrument," Gallagher said.
"We here at Marshall and at the University of Alabama in
Huntsville have a great deal of expertise in ultraviolet optics
and experience in auroral imaging."

WIC builds on the team's experience with the Ultraviolet Imager
(UVI) now operating aboard the Polar spacecraft. UVI provides
images of the aurora borealis on both night and day sides of
the northern hemisphere.

The WIC will be sensitive to light in the 140-160 nm range
(visible light spans 300-700 nm). It will have a 17x17-degree
field of view (about 34 times the apparent diameter of the Moon)
so it can see the entire Earth.

WIC is one of three cameras in the far-ultraviolet instrument.
The Spectrographic Imager will measure different types of aurora
and remove the bright geocorona emissions from the images. The
Geocorona Photometers will observe the distribution of the geocorona
emissions to derive the magnetospheric hydrogen content responsible
for neutral atom generation in the magnetosphere.

Three other types
of instruments will be on IMAGE. A battery of three neutral atom
imagers will detect the presence of atoms by recording the light
given off when they collide with hydrogen atoms. A Radio Plasma
Imager will make cross-sectional images somewhat like a medical
CT-scan, by using the echoes from radio pulses broadcast by the
satellite. And the extreme-ultraviolet (EUV) imager will take
pictures at 30.4 nm of sunlight scattered by helium ions in the
plasmasphere, a donut-shaped region mostly containing hydrogen,
helium, and oxygen ions.

Left: The Wideband Imaging Camera shortly after it completed
testing.

An open treasure chest

Unlike most other science missions, all the data from IMAGE's
instruments will be made available to anyone as soon as it arrives.
Traditionally, NASA has given the principal investigator exclusive
use of the data for up to a year after it arrives.

The IMAGE Team

The IMAGE Principal
Investigator is Dr. James L. Burch, Southwest Research Institute,
San Antonio, Texas. The project is managed by NASA's Goddard
Space Flight Center. At NASA/Marshall participants include Dr.
Dennis Gallagher, co-investigator, and Dr. James Spann, participating
scientist.

"This is going to be an open data set," Gallagher
said. "Our ambition is that from the first data set that
comes to the ground, starting about a month after launch, there
will be browse data on the worldwide web for anyone to look at.
The data will come down the Deep Space Network, and into the
Satellite Mission Operations Center. The data packets are wrapped
and archived."

CD-ROMs containing high-resolution data (cleansed of noise
and formatted for use) will be sent to the principal investigators
and to the National Space Science Data Center at NASA's Goddard
Space Flight Center in Greenbelt, Md. Any scientist can access
IMAGE data to explore the magnetosphere.

"It's going to be an exciting time," Gallagher said.
"Every time you figure out a new way to measure your environment,
whether it's the universe or microscopic, you see things you
didn't think would be there. You learn. That's what research
is about. You learn more about the environment in new ways."